In general, as illustrated in FIG. 1, a drum type washing machine is provided with a laundry loading/unloading opening 101 that is closed by a door at the front of an outer case 100 and laundry such as clothes is introduced there into through the laundry loading/unloading opening 101. A cylindrical tub 102 with a bottom is placed horizontally in the outer case 100. A cylindrical drum 103 having a bottom and a circumferential wall provided with a plurality of through-holes is rotatably disposed in the tub 102. A series of processes of washing, rinsing, and spin-drying are automatically performed in a state where clothes are contained in the drum 103.
The tub 102 may be disposed such that an opening is positioned adjacent to the laundry loading/unloading opening 101 to face the laundry loading/unloading opening 101. The tub 102 may be elastically supported by the outer case 100 by using a suspension or the like. A gap between the opening of the tub 102 and the laundry loading/unloading opening 101 may be sealed by an elastic packing material or the like to prevent water leakage.
The tub 102 becomes in an approximately sealed state by closing the door of the laundry loading/unloading opening 101 when it is in use. However, it is not an airtight state but a so-called watertight state. That is, even in washing, rinsing, and spin-drying cycles, the inside of the tub 102 generally communicates with the outside via a water supply path or a drain path disposed at radially outward portions of the tub 102. Thus, air may flow out of the tub 102.